This invention relates to a process for preparation of telechelic difunctional unsaturated oligomers and polymers having at least one internal carbon-to-carbon double bond by olefin cross-metathesis of acyclic polyenes in the presence of a functionalized olefin containing at least one reactive component selected from the group consisting of a nitrile, ester, alcohol, diol, amine, acid, acyl halide, ketone, aidehyde, borane, amide, acid anhydride, ether, imide, halogen atom, alkyne, alkyl, aryl, and a substituted aryl group, employing a catalyst composition comprising (A) a transition metal chloride, oxyhalide, oxide or ammonium salt, (B) an organic tin compound or aluminum halide reagent and (C) an organic Lewis base wherein undesired side reactions such as double bond migration are minimized and the functionality of the product is about 2. With acyclic polyenes and functionalized olefin reactants, the process yields telechelic difunctional unsaturated oligomers and polymers having at least one internal carbon-to-carbon double bond such as alpha, omega difunctional polybutadienes with acetoxy (OAc) endgroups from the reaction of 1,5-hexadiene and 4-pentenyl acetate. These telechelic difunctional unsaturated oligomers and polymers with terminal endgroups are suitable for further functionalization or incorporation into other polymers for preparation of block copolymers, ion exchange resins, adhesives and flocculants.
Acyclic unsaturated compounds containing functional groups have been prepared by the olefin metathesis reaction. The metathesis of unsaturated ethers, amines and chlorides has been reported (K. J. Ivin, Olefin Metathesis, Academic Press, London, N.Y., 149, 1983) as the result of no inherent conflict between the functional groups and the metal carbene bond. However, it is reported that the interaction of the catalyst complex with functional groups of the subject olefin can be critical.
As is well known, side reactions can occur during olefin metathesis reactions. These side reactions include alkylation, isomerization, cyclization and addition across double bonds present in the molecular structure. Surprisingly, it has been found that in a cross-metathesis reaction between a polyene and a olefin under the conditions of the present invention, these side reactions are minimal. Functionality of oligomers and polymers prepared by the process of this invention is about 2.
This invention relates to preparation of acyclic telechelic difunctional unsaturated oligomers and polymers having at least one internal carbon-to-carbon double bond by means of an olefin cross-metathesis reaction in the presence of a catalyst system for such reaction and in the presence of a functionalized olefin. In one aspect, this invention relates to the conversion of acyclic polyenes to acyclic telechelic difunctional unsaturated olefinic compounds by disproportionation or cross-metathesis of two olefins and to the oligomers and polymers derived therefrom having a functionality of about 2. In another aspect, it relates to the olefin cross-metathesis reaction of acyclic polyenes in the presence of a functionalized olefin containing at least one functional group wherein undesired side reactions, or little or no double bond migration or cyclization, occur. Depending upon the nature of the functional terminal end-group of the acyclic difunctionalized unsaturated oligomer and polymer, the products of the olefin metathesis reaction are useful in the preparation of other compounds such as segmented copolymers.
The disproportionation or metathesis of olefins is a reaction in which one or more olefinic compounds are transformed into other olefinic compounds of different molecular weights. The disproportionation of an olefin to produce an olefin of higher molecular weight and an olefin of lower molecular weight can be a self-disproportionation reaction as propylene to ethylene and butene, or co-disproportionation of two different olefins to produce still other olefins, also termed cross-metathesis of olefins.
The utility of the olefin disproportion reaction, commonly termed an olefin metathesis reaction, has been recognized as a means to obtain olefinic compounds bearing functional reactive groups such as esters, ethers, halogens and others. However, inasmuch as the olefin metathesis reaction is an equilibrium reaction of unsaturated compounds, the usual consequences of an equilibrium reaction can be present, i.e., yields of the desired product can be low unless a suitable means of driving the reaction to completion can be utilized. Also, the catalyst present to initiate olefinic metathesis can initiate by-product reactions. The reverse of the olefinic metathesis reaction can occur wherein the reaction products self-metathesize to form other olefinic compounds. Terminal olefins have been found to self-metathesize rapidly such as in the industrial process for conversion of propylene to other products. The cis-trans configuration of the final product may be predominantly trans, or predominantly cis, or a mixture of cis-trans, depending upon reaction conditions, including the catalyst utilized.
The disproportionation of olefins bearing functional groups is an especially economically useful reaction in that the products bearing functional groups have been available and valuable for use in polymer formation and chemical transformations to yield industrially valuable products. Examples of functional reactive groups previously available are esters, hydroxides, amines, halides. However, difunctional hydrocarbon oligomers and polymers having at least one internal carbon-to-carbon double bond wherein the functional groups are terminal reactive groups have not been previously prepared from acyclic polyenes by metathesis reaction except by a difficult and not easily-available catalytic process.
Telechelic polymers having functional groups usable for further reactions, i.e., cross-linking reactions or the construction of other defined polymer structures such as block copolymers, etc., are of great interest from the viewpoint of possible applications. A polymer halogen-terminated at both ends can be reacted with a metal-terminated chain of another polymer to produce block copolymers. Hydroxy-terminated polymer chains can be reacted with di- and/or tri- polyisocyanates and/or analogous polyfunctional compounds such as acid chlorides of polybasic acids.
Telechelic difunctional polymers have been prepared in the past by termination of living polymers with anionic, cationic and metathesis polymerizations of cyclic olefins. Metathesis polymerizations of cyclic olefins can restrict the availability of products available to those which can be prepared from a relatively few cyclic olefins, typically of from about 5 to about 9 carbon atoms. Difunctional polymers derived from cyclic olefins can be limited in functional groups to those of the precursor cyclic olefins. With acyclic olefins, the olefin metathesis reaction with cleavage and reforming of carbon-to-carbon double bonds, the redistribution of alkylidene moleties leads to a random product distribution at equilibrium (Kirk-Othmer, Ency. Chem. Tech., 597, 3rd ed., Vol. 8). Telechelic difunctional hydrocarbon oligomers/polymers produced via anionic or free-radical polymerizations of acyclic olefins typically are mixtures of polymer structures. For example, alpha-omega difunctional polybutadienes prepared by anionic or free-radical polymerization of butadiene contain mixtures of 1,4-and 1,2-polybutadiene structures, have molecular weights of 1000-4000 and are terminated with hydroxy or carboxy functionalities. Typically, the functionalities are less than difunctional, the functionality number being less than 2; or greater than difunctional, the functionality number being greater than 2, the products being mixtures of functional endgroups, e.g., mono-functional, difunctional, and non-functional.